This invention relates to fibre-optic cable assemblies.
Fibre-optic cable assemblies comprise one or more optical fibres extending within an outer sheath provided with a termination in which the or each fibre is retained. In high temperature applications the fibres are typically of silica and the sheath includes a metal tube, so they have dissimilar coefficents of expansion. This can lead to difficulties at the terminations because, if the tube is rigid axially, the terminations must allow some relative longitudinal movement between the termination and fibre in order to accommodate differential thermal expansion between the fibre and sheath. Flexing of the cable can also lead to relative longitudinal movement between the fibres and sheath. The difficulties are increased because of the need to maintain the fibres accurately located within the termination for maximum efficiency of optical coupling. It is also desirable to prevent sliding movement both between the fibres and over any part of the termination because this can lead to wear and fatigue. The termination should, furthermore, provide an effective seal with the fibres in order to prevent ingress of contaminants to the cable.